Muffler arrangement for hermetic compressors



R. L. DILLS 2,935,244

MUFFLER ARRANGEMENT FOR HERMBTIC COMPRESSORS May 3, 1960 Filed May 8, 1958 INVENTOR.

RAYMOND L. DILL. s

HIS ATTORNEY United States Patent MUFFLER ARRANGEMENT FOR HERMETIC COMPRESSORS Raymond L. Dills, Louisville, Ky., assignor to General Electric Company, a corporation of New York Application May 8, 1958, Serial No. 733,964

3 Claims. (Cl. 230-58) The present invention relates to hermetic compressors and is more particularly concerned with a motor-driven compressor so designed that the motor and motor housing serve as a muffler or acoustic absorber arrangement to dampen intake gas pulses.

Because compressors of the type employed for example in household refrigerators are normally operated in an environment having a relatively low noise level, it is desirable to eliminate or minimize the noises resulting from the operation of the compressor. In a reciprocating compressor the valves controlling the flow of gas to and from the compressor cylinder and the pulsating movement of the gas to and from the compressor due to the operation of the valves requires both intake and exhaust mothers to dampen the pulses and thereby avoid resonance of other parts of the system such as the compressor case.

The present invention is particularly concerned with the noise problems resulting from intake gas pulses and has as its primary object the provision of a motor-driven compressor designed to eliminate the need for the usual intake muffler as a separate or added item to prevent vibration of the hermetic casing and other parts of the refrigerating system due to reaction to the intake gas pulses.

A further object of the invention is to provide a low cost arrangement for dampening intake pulses in a low side hermetically sealed compressor unit.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In carrying out the objects of the present invention there is provided a hermetic compressor unit comprising a compressor and a motor for driving the compressor sealed within a hermetic casing. The unit includes a housing which supports the motor and which encloses one end of the motor in such a manner that the motor and housing form a closed chamber between the motor and the compressor cylinder. In order to eliminate the usual intake mufller for suppressing or absorbing intake gas pulses, the unit is so designed that this closed chamber and the motor end turns contained within the chamber provide the desired mufiiing action for intake or suction gas flowing from the low side hermetic casing through the motor and chamber to the compressor intake port. In order that the end turns of the stator wire and coils will serve as acoustic absorbers for intake gas pulses, it is preferred that during operation of the compressor these end turns be continuously bathed by a stream of lubricating oil flowing over the end turns and permeating the interstices or spaces betweenthe individual wires or For a better understanding of the invention reference may be had to the accompanying drawing in which:

Fig. 1 is an elevational view, partly in section, of a hermetically sealed compressor embodying the present invention; and

Fig. 2 is a sectional view of a portion of the motor of Fig. 1 taken along line 2-2 of Fig. 1.

With reference to the drawing there is shown a hermetic compressor unit including a casing 1 containing a compressor 2 and a motor 3 hermetically sealed within the casing 1. A supporting frame including a housing 4 having bearings 5 in the vertical wall 6 of the housing supports the horizontal drive shaft 10 connecting the motor rotor 7 with the eccentric 13 for driving the piston 8 forming part of the compressor structure 2. It will be understood that the frame is suitably supported by means of a plurality of springs within the casing 1, the springs serving to minimize as much as possible the transmission of compressor vibrations and noise to the casing and to protecting the motor compressor unit from handling and other severe shocks.

As will be seen from Fig. 1 of the drawing the stator 9 of the motor 3 is directly supported by the cylindrical wall 11 of the housing 4 in spaced relationship with the wall 6 so that there is defined between the motor and the V compressor a chamber 12.

The compressor 2 is supported on the opposite side of the wall 6 from the motor by means of a bracket 14 suitably secured mechanically to the wall 6. The compressor includes the usual valve controlled intake port 15 for admitting gas to the compressor cylinder 16 during each down stroke of the piston 8 and valve controlled exhaust port 19 through which the compressed gas is exhausted to the exhaust mufller 20 and outside of the compressor case through the conduit 21 during each upward stroke of the piston 8. The usual exhaust mufiier 20 is provided as an acoustic absorber for exhaust gas pulses in order that the high noise energy of these exhaust gases will not be transmitted to the case through the flexible conduit 21 or to the remaining portion of the systemwhen the compressor forms part of the refrigerating system.

In accordance with the present invention, the chamber 12 and its contents including the end turns 22 of the motor or stator windings comprise acoustic absorber means to damp the intake gas pulses. For this purpose the inlet passage to the inlet port 15 of the compressor,

is in the form of a passage 23 extending through the bracket 14 and connecting the port with the chamber 12 through the wall 6 of the housing 4. By this arrange- I ment, low pressure gas entering the case through the suction line or inlet 25 passes from the interior of the a casing 1 to the chamber 12 through the unfilled portions of the slots 26 provided in the stator for holding the stator windings.

While the tightly wrapped end coils or turns 22, which preferably fill at least one third of the chamber 12, provide a substantial absorbing action for the noise energy of the intake gas flowing to the passage 23, a much higher muifling action is obtained when the end coils 22 are continuously bathed by a flowing stream of lubricatingoil so that the interstices or spaces between the wires comprising these end turns 22 are filled with oil thus, damping the vibration of the end coils or the individual wires comprising these coils due to'the noise energy of the intake gas.

' oil by maintaining a continuous flow of damping oil over these end turns and also for the purpose of cooling the motor, oil is continuously withdrawn from the oil sump 31 provided in the bottom of the case 1 through a conduit 32 by means of an oil pump 33 driven by the shaft it"). From the oil pump 33, oil flows through the tube 34 having its discharge end 35 positioned in the chamber 12 above the upper portion of the end turns 22. Oil issuing from the outlet 35 flows downwardly over the end turns 22 arranged at the top of the motor 3. The oil shield 36 which is supported along one edge of the slots 26 across .the upper half of the motor prevents the oil from flowing directly onto the rotor element 7. The oil caught by the oil shield 36 flows downwardly onto the lower end turns 22 where it impregnates these turns for damping and cooling purposes. The oil then returns to the sump 31 through the tubular element 4% immersed in the oil sump and communicating with the lower portion ofthe chamber 12 and also through the slot 41 provided in the lower portion of the stator 9. Normally, there will be a head of oil indicated by the number 43 within the lower part of the chamber 12 due to the fact that during operation of the compressor the pressure within the chamber 32 is slightly lower than in the casing 1.

For the purpose of providing a small amount of lubrication for the compressor cylinder 16 and the valves controlling the inlet and outlet ports 15 and 19, a small amount of oil from the oil pump 33 is allowed to pass along shaft it) and outwardly onto the counterweight 44 positioned on the shaft ll) between the bracket 14 and the compressor 2. Oil flowing onto the counterweight 44 is thrown off of the end thereof during rotation and a portion of this oil strikes the lower inclined surface 45 on the bracket 12 from which it is drawn through the opening 45 communicating with the passage 3 by the action of the compressor 2. This lubricant picked up by the suction gas flowing to the compressor lubricates and damps the valves controlling the inlet and exhaust ports and also serves to lubricate the piston 8.

From the above description it will be seen that there has been provided in accordance with the present invention a motor compressor unit in which the motor components including the stator wire and the motor support housing effectively muffle the intake gas pulses. For best results it is essential that the end turns of the stator wire within the chamber between the motor and the cornpressor intake passage be supplied with sufiicient oil that the end turns will be as completely saturated with oil both for :the purpose of decreasing the acoustic vibration of the individual wires forming the end turns and for the purpose of aiding these end turns in functioning as acoustic absorbers to prevent the noise energy of the intake gas pulses from being transmitted back to the casing 1.

While the present invention has been described by reference to a particular embodiment thereof, it will be understood that modifications may be made therein by those skilled in the art without actually departing from the invention. Therefore, in the appended claims it is intended to cover all such variations as come within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A hermetically sealed refrigerant compressor comprising a sealed casing having an oil sump therein and a low pressure gas inlet therethrough, a reciprocating compressor including valve controlled intake and exhaust ports for withdrawing low pressure refrigerant from said casing and discharging compressed refrigerant exteriorly of said casing, an electric motor for driving said compressor, a horizontal drive shaft connecting said motor and compressor, a frame supporting said motor and com pressor and including a housing supporting the stator component of said motor and surrounding one end of said motor to form therewith a closed chamber between said motor and said compressor, an intake passage com necting said chamber with the compressor intake port, said stator component including a plurality of slots and motor windings partially filling said slots and having end turns composed of a plurality of coils extending into and filling at least one-third of said chamber, said slots forming passages for flow of low pressure refrigerant from said casing to said chamber, and means for circulating oil from said sump over said end turns in an amount sufficient to saturate said end turns with oil, said chamber and the oil-saturated end turns therein forming an acoustic absorber to absorb and dissipate vibrations resulting from pulsating flow of gas to said compressor intake port during operation of said compressor.

2. A hermetic compressor comprising a sealed casing having an oil sump in the bottom thereof, a motor-compressor unit supported within said casing above the level of the oil in said sump; said motor-compressor unit comprising a housing including a bearing in a vertical wall thereof and a horizontally extending shaft journalled in said bearing, a compressor supported on one side of said vertical wall in spaced relationship therewith and connected to said shaft, a motor having a stator supported by said housing and rotor mounted on the other end of said shaft within said housing, said motor being in spaced relationship with said vertical wall, said motor and said housing defining a closed chamber between said motor and said compressor, slots in said stator, stator windings partially filling said slots and having end turns extending into said chamber and filling at least one-third of the volume of said chamber, said compressor including a suction gas conduit having its inlet end communicating with said chamber, a lubricating and motor cooling system including an oil pump for withdrawing oil from said sump and directing oil over said end turns within said chamber for cooling said motor, means for returning oil from said chamber to said sump including an oil return tube at the bottom of said chamber and having an outlet end below the level of oil in said sump, said end turns in cooperation with the oil flowing over and between the individual coils thereof functioning as acoustic absorbers for intake pulses of gas flowing from said casing through said slots and into said cylinder.

3. A hermetic compressor comprising a sealed casing having an oil sump in the bottom thereof, a motor-compressor unit supported within said casing above the level of the oil in said sump; said motor-compressor unit comprising a housing including a bearing in a vertical wall thereof and a horizontally extending shaft journalled in said bearing, a compressor supported on one side of said vertical wall in spaced relationship therewith and connected to said shaft, a motor having a stator supported by said housing and a rotor mounted on the other end of said shaft within said housing, said motor being in spaced relationship with said vertical wall, said motorand said housing defining a closed chamber between said motor and said compressor, slots in said stator, stator windings partially filling said slots and having end turns extending into said chamber and filling at least one-third of the volume of said chamber, said compressor including a suction gas conduit having its inlet end communicating with said chamber, a counterweight carried by said shaft between said housing and said compressor, a lubricating and motor cooling system including an oil pump for withdrawing oil from said sump and directing a first portion over said end turns within said chamber for cooling said motor and a second portion onto said counterweight, an oil hole connected to said suction gas conduit outside said housing having its inlet one in the path of the oil centrifugally discharged from said counterweight dur ng operation of said motor whereby lubricant is supplied to said compressor, means for returning oil from said chamber to said sump including an oil return tube at the bottom of said chamber and having an outlet end be low the level .of oil in said sump, said end turns in cooperation with the oil flowing over and between the .in-

5 v i a 6 dividual coils thereof functioning as acoustic absorbers 2,504,528 Hume Apr. 18, 1950 for intake pulses of gas flowing from said casing through 2,738,961 M'athers Mar. 20, 1956 said slots and into said cylinder. 2,741,424 Ploeger Apr. 10, 1956 2,844,302 Weibel July 22, 1958 References Cited in the file of th1s patent 5 2,846,140 Kemper Aug. 5, 1958 UNITED STATES PATENTS 2,283,024 Wolfert May 12, 1942 FOREIGN PATENTS 2,485,555 Bester Oct. 2 1 4 931,232 Germany July 7, 195 

